pope benedict xvi been said it's time for someone physically stronger to leave the cat like church. >> reporter: the contest making this stunning announcement at a meeting with his cardinals. >> and he plans to retire at the end of themont. >> i'm shocked as much as you. >> reporter: even though he's aware of the seriousness of stepping down, he doesn't have the strength to carry out his papal duties saying, quote, both strength and mind and body are necessary. strength, which in the last few months, did tireiated in me. >> i always admired him as a scholar, as a priest, as a holy man. and now my admiration is higher because his humility. >> reporter: he's 85 years old, the first german pope in hundreds of years. elected in 2005, he succeeded john paul ii. there have been recent concerns about his health and he's needed help walking, but a vatican spokesperson insists he's not facing anything grave. the cardinals will elect his replacement and hope that can happen by holy week. >> they're looking for someone to preserve the court teachings of the church and be a faith in the church. >